;(function (win, lib) {
	var doc = win.document
	var docEl = doc.documentElement
	var metaEl = doc.querySelector('meta[name="viewport"]')
	var flexibleEl = doc.querySelector('meta[name="flexible"]')
	var dpr = 0
	var scale = 0
	var tid
	var flexible = lib.flexible || (lib.flexible = {})

	if (metaEl) {
		console.warn('将根据已有的meta标签来设置缩放比例')
		var match = metaEl
			.getAttribute('content')
			// eslint-disable-next-line no-useless-escape
			.match(/initial\-scale=([\d\.]+)/)
		if (match) {
			scale = parseFloat(match[1])
			dpr = parseInt(1 / scale)
		}
	} else if (flexibleEl) {
		var content = flexibleEl.getAttribute('content')
		if (content) {
			// eslint-disable-next-line no-useless-escape
			var initialDpr = content.match(/initial\-dpr=([\d\.]+)/)
			// eslint-disable-next-line no-useless-escape
			var maximumDpr = content.match(/maximum\-dpr=([\d\.]+)/)
			if (initialDpr) {
				dpr = parseFloat(initialDpr[1])
				scale = parseFloat((1 / dpr).toFixed(2))
			}
			if (maximumDpr) {
				dpr = parseFloat(maximumDpr[1])
				scale = parseFloat((1 / dpr).toFixed(2))
			}
		}
	}

	if (!dpr && !scale) {
		// eslint-disable-next-line no-unused-vars
		var isAndroid = win.navigator.appVersion.match(/android/gi)
		var isIPhone = win.navigator.appVersion.match(/iphone/gi)
		var devicePixelRatio = win.devicePixelRatio
		if (isIPhone) {
			// iOS下，对于2和3的屏，用2倍的方案，其余的用1倍方案
			if (devicePixelRatio >= 3 && (!dpr || dpr >= 3)) {
				dpr = 3
			} else if (devicePixelRatio >= 2 && (!dpr || dpr >= 2)) {
				dpr = 2
			} else {
				dpr = 1
			}
		} else {
			// 其他设备下，仍旧使用1倍的方案
			dpr = 1
		}
		scale = 1 / dpr
	}

	docEl.setAttribute('data-dpr', dpr)
	if (!metaEl) {
		metaEl = doc.createElement('meta')
		metaEl.setAttribute('name', 'viewport')
		metaEl.setAttribute(
			'content',
			'initial-scale=' + scale + ', maximum-scale=' + scale + ', minimum-scale=' + scale + ', user-scalable=no'
		)
		if (docEl.firstElementChild) {
			docEl.firstElementChild.appendChild(metaEl)
		} else {
			var wrap = doc.createElement('div')
			wrap.appendChild(metaEl)
			doc.write(wrap.innerHTML)
		}
	}

	function refreshRem() {
		var width = docEl.getBoundingClientRect().width
		// 最小1366px，最大适配2560px
		// if (width / dpr < 1366) {
		//   width = width * dpr;
		// }  else if (width / dpr > 1900) {
		//   width = width * dpr;
		// }
		// else if (width / dpr > 2560) {
		//   width = width * dpr;
		// }
		// 设置成24等份，设计稿时1920px的，这样1rem就是80px
		var rem = width / 24
		docEl.style.fontSize = rem + 'px'
		flexible.rem = win.rem = rem
	}

	win.addEventListener(
		'resize',
		function () {
			clearTimeout(tid)
			tid = setTimeout(refreshRem, 300)
		},
		false
	)
	win.addEventListener(
		'pageshow',
		function (e) {
			if (e.persisted) {
				clearTimeout(tid)
				tid = setTimeout(refreshRem, 300)
			}
		},
		false
	)

	if (doc.readyState === 'complete') {
		doc.body.style.fontSize = 12 * dpr + 'px'
	} else {
		doc.addEventListener(
			'DOMContentLoaded',
			// eslint-disable-next-line no-unused-vars
			function (e) {
				doc.body.style.fontSize = 12 * dpr + 'px'
			},
			false
		)
	}

	refreshRem()

	flexible.dpr = win.dpr = dpr
	flexible.refreshRem = refreshRem
	flexible.rem2px = function (d) {
		var val = parseFloat(d) * this.rem
		if (typeof d === 'string' && d.match(/rem$/)) {
			val += 'px'
		}
		return val
	}
	flexible.px2rem = function (d) {
		var val = parseFloat(d) / this.rem
		if (typeof d === 'string' && d.match(/px$/)) {
			val += 'rem'
		}
		return val
	}
})(window, window['lib'] || (window['lib'] = {}))
